Gta 4 problems

I have multiple problems in gta 4 that I would like to be fixed....
the game keeps on loading and requires a file "commandline.txt' for ot to load...so it fixes the first problem....but it creates other problems....I cannot change in-game settings and need to type them in the commandline.txt , which is frustrating.... And the worse of all...I , even though having very high end pc for games like gta 4....have to set the settings very very low for smooth performance (even lower than what I use in crysis 3 and assassins creed black flag , which are far far faaar more demanding )
Plzz help..